Second Firefox 36.0.1 starts to black screen

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For bugs in Firefox Desktop, the Mozilla Foundation's web browser. For Firefox user interface issues in menus, developer tools, bookmarks, location bar, and preferences. Many Firefox bugs will either be filed here or in the Core product. (more info)

Security

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User Story

User Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:36.0) Gecko/20100101 Firefox/36.0
Build ID: 20150305021524
Steps to reproduce:
Start first Firefox and log into e.h. eBay. Launch second copy of Firefox with either a shortcut or start menu (not a tab in the first copy).
Actual results:
Second copy ALMOST always comes up with black screen. If, however, you first start a second tab in the first session using the "+", and THEN launch a second Firefox using the shortcut, it starts correctly. Safemode startup does not fix the problem.
Expected results:
Second Firefox should launch with startup screen.
Environment: Win 7 SP1 fully updated 64-bit, Dell 760 Core2 Duo E7400 @ 2.8GHz with 4GB RAM Intel Q45/Q43 Chipxet graphics.